21 



The only experiment against insects was a treatment, twice repeated, 

 against the Euonymus scale. At tlie time of tlie application tlic young 

 scales were enjerging in great numbers, and the strength employed was 

 the 0.2 gauge, indicating 20 per cent of kerosene. Samples of oil were 

 taken at intervals during the spraying and indicated an ac^tual strength 

 of oil ranging from 14 to 19 per cent. Examination of the scales a 

 week after spraying indicated that 80 per cent of the young scales and 

 50 per cent of all scales, young and old, were killed — a result far from 

 satisfactory, and indicating that the kerosene emulsion at much weaker 

 strength of oil is more effective; doubtless because, being of thicker 

 consistency, it is more persistent in its action, whereas the water and 

 oil both evaporate somewhat rapidly. Xo injury to the bushes resulted 

 even after a second application at the same strength had been made. 

 The second application resulted in the destruction of about the same 

 percentage of the surviving scales as succumbed to the iirst treatment. 



The spray as it comes from the nozzle is milky in color, and when col- 

 lected in graduated receivers is of the ai^pearance of milk. Although 

 beginning to separate immediately, the separation is not complete in 

 some cases for several hours. There can be no question that when the 

 liquid strikes the jilants the oil is as finely divided as it is in the kerosene 

 emulsion. Wherever it colle cts in drops, however, the oil of course will 

 separate from the water; but, from actual experience in spraying, this 

 does not seem to be a very great source of danger at the 10 per cent 

 strength, which would be considered a i^retty strong wash even with 

 kerosene emulsion. In the case of the collection of the liquid in drops 

 the oil which separates is not very considerable, and its influence is 

 modified by the existence of the underlying stratum of water, the slow 

 evaporation of which allows the oil to act on the i^lant very gradually. 

 The fact that the strength indicated did not injure the tender foliage of 

 the plants is a strong indication that the principle involved is a valuable 

 one and may possibly be made of great service. The objections urged 

 are, therefore, simply in the way of pointing out defects in this partic- 

 ular apparatus, all of which it will probably be i)08sible to correct. 



Parallel experiments by apx)lication to plants were made with 

 kerosene and whale-oil soap emulsion, the emulsion being used at a 

 strength to give the same percentage of oil obtained with the knap- 

 sack i)ump. The results on the foliage were equally favorable in the 

 latter case. Xo injury whatever was done. All of the plants sprayed 

 with kerosene and Avater were treated with the kerosene emulsion with 

 the exception of the mulberry, of which we had only one small tree for 

 exi)eriment. The important points to be noted in correcting this api)a 

 ratus by the parties who are interested in its manufacture are, first? 

 to insure a uniform percentage of oil for any reasonable condition of 

 tanks as to fullness; second, to make the tank absolutely independent, 

 as well while the i)umping is in operation as when the stopcocks are 

 shut oli'. The remedying of these two defects should i)revent the more 



